1. Field of the Invention
The present invention relates to a pneumatic nailer, and more particularly, to a device with a function of the rapid switching between single and sequential discharge of fasteners.
2. Description of the Prior Art
The conventional pneumatic nailer makes use of the compression air for driving fasteners into woody or plastic objects for fixing. The discharge force is extremely strong and is dangerous to a certain extent. Therefore, the conventional nailer is fitted with a safety apparatus, as shown in FIG. 7. The so-called safety apparatus includes a safety inflection arm 11 provided at front end of a mouth of a gun body. When the front end of the safety inflection arm 11 is pressed in a coupled manner, a connecting rod 12 at rear end thereof is in pressing contact against a secondary trigger 14. When the primary trigger 13 is pulled back, the secondary trigger 14 is slightly moved inwards to press against a firing key 15 for completing the discharge action. Thereafter, if the user doesn""t release the safety inflection arm 11, the secondary trigger 14 won""t complete a second discharge due to an improper contact thereof with the connecting rod 12. Thus, an unexpected second discharge is avoided. However, it""s impractical that another discharge can be performed only after release of the safety inflection arm 11. Accordingly, a bar 16 is pivotably arranged parallel to and below the safety inflection arm 11. This bar 16 is pivotable between a protruding and hidden state while the other end thereof is positioned by means that a steel ball 17 and a spring 18 press against it. When the bar 16 is situated at a protruding position, as shown in FIG. 8, and is shifted with the safety inflection arm 11 to contact with the secondary trigger 14, a sequential ordinary contact state of the safety inflection arm 11 with the secondary trigger 14 is ensured to create a sequential discharge. However, the pivotal position of the bar 16 inside the gun body is bad and the installation of the positioning elements is impractical so that following drawbacks in use and in assembly are caused:
1. In pivotable installation of the bar, the spring and the steel ball have to be placed in a receptacle. The receptacle is situated at the inner rim of a mounting seat on which the bar is pivotably mounted. Therefore, it""s time-wasting and energy-consuming in assembling the spring and the steel ball. Besides, the steel ball is pressed by the spring and positioned at one end of the bar so that the steel ball is easily separated from the receptacle by being pressed by the spring before installation of the bar.
2. In use, as shown in FIGS. 7 and 8, the bar is pivotably arranged between the primary trigger and the safety inflection arm. The arrangement space is too small. Besides, it""s not easy that the bar is moved when it""s pivotably mounted at the mounting seat and restrained by the steel ball. It""s not only to cause inconvenience in use, but also easily lead to knocking injuries of fingers in case of carelessness.
It is a primary object of the present invention to overcome the drawbacks associated with the prior art and to provide an adjusting apparatus of a trigger of a pneumatic nailer, wherein the adjustable apparatus is movable between two shaft holes of a primary trigger so as to rapidly adjust the relative position between a secondary trigger and a safety inflection arm. Accordingly, the single and sequential discharge of the gun body is more easily switchable.